Underestimated Amoebic Appendicitis among HIV-1-Infected Individuals in Japan. J Clin Microbiol. 2017;55:313-320. [PMID: 27847377 PMCID: PMC5228245 DOI: 10.1128/jcm.01757-16]

Molecular characterization and zoonotic potential of Entamoeba spp., Enterocytozoon bieneusi and Blastocystis from captive wild animals in northwest China

BACKGROUND

Parasites Entamoeba spp., Enterocytozoon bieneusi and Blastocystis are prevalent pathogens causing gastrointestinal illnesses in animals and humans. Consequently, researches on their occurrence, distribution and hosts are crucial for the well-being of both animals and humans. Due to the confined spaces and frequent interaction between animals and humans, animal sanctuaries have emerged as potential reservoirs for these parasites. In this study, the wildlife sanctuary near the Huang Gorge of the Qinling Mountains in northwest China is chosen as an ideal site for parasite distribution research, considering its expansive stocking area and high biodiversity.

RESULTS

We collected 191 fecal specimens from 37 distinct wildlife species and extracted genomic DNA. We identified these three parasites by amplifying specific gene regions and analyzed their characteristics and evolutionary relationships. All the parasites exhibited a high overall infection rate, reaching 90.05%. Among them, seven Entamoeba species were identified, accounting for a prevalence of 54.97%, with the highest infection observed in Entamoeba bovis. In total, 11 Enterocytozoon bieneusi genotypes were discovered, representing a prevalence of 35.08%, including three genotypes of human-pathogenic Group 1 and two novel genotypes (SXWZ and SXLG). Additionally, 13 Blastocystis subtypes were detected, showing a prevalence of 74.87% and encompassing eight zoonotic subtypes. All of the above suggests significant possibilities of parasite transmission between animals and humans.

CONCLUSIONS

This study investigated the occurrence and prevalence of three intestinal parasites, enhancing our understanding of their genetic diversity and host ranges in northwest China. Furthermore, the distribution of these parasites implies significant potential of zoonotic transmission, underscoring the imperative for ongoing surveillance and implementation of control measures. These efforts are essential to mitigate the risk of zoonotic disease outbreaks originating from wildlife sanctuary.

Amebiasis as a sexually transmitted infection: A re-emerging health problem in developed countries

Amebiasis, which is caused by Entamoeba histolytica (E. histolytica), is the second leading cause of parasite-related death worldwide. It manifests from asymptomatic carriers to severe clinical conditions, like colitis and liver abscesses. Amebiasis is commonly seen in developing countries, where water and food are easily contaminated by feces because of the poor sanitation. However, a recently challenge in many developed countries is the increase in domestic cases of invasive amebiasis as a sexually transmitted infection (STI amebiasis). In contrast to food-/ waterborne transmission of E. histolytica in developing countries, transmission of STI amebiasis occurs directly through human-to-human sexual contact (e.g., men who have sex with men and people who engage in oral-anal sex); in this setting, asymptomatic infected individuals are the main reservoir of E. histolytica. The Development of screening methods for the early diagnosis of asymptomatic E. histolytica infection is the key to epidemiologic control. Moreover, delay in diagnosis of severe cases (e.g., fulminant amebiasis) leads to death even in developed countries. It is also important to increase clinical awareness of domestically transmitted STI amebiasis in the clinical settings. This review considers the changing epidemiology and clinical manifestations of STI amebiasis, and finally discusses the future strategies for the better practice.

Acute appendicitis secondary to Entamoeba histolytica infestation

Acute appendicitis secondary to amoebic infestation is a rare possibility, especially in endemic areas. If left untreated, significant postoperative morbidity and mortality can result from the spread of amoebic trophozoites and subsequent tissue reaction. Histopathological examination of the resected appendix with demonstration of invasion by the parasite is mandatory for establishing a diagnosis. Careful examination of the specimen is thus of paramount importance.

Emergency appendectomy versus elective appendectomy following conservative treatment for acute appendicitis: a multicenter retrospective clinical study by the Japanese Society for Abdominal Emergency Medicine

PURPOSE

To establish the best treatment strategy for acute appendicitis.

METHODS

We collected data on 2142 appendectomies performed in 2017 and compared the backgrounds and surgical outcomes of patients who underwent early surgery (ES) (< 48 h) with those managed with non-ES (> 48 h). We performed a risk factor analysis to predict postoperative complications and subgroup analysis to propose a standard treatment strategy.

RESULTS

The incidence of postoperative complications was significantly higher in the ES group than in the non-ES group, and significantly lower in the laparoscopic surgery group than in the laparotomy group. Surgical outcomes, including the incidence of postoperative complications, were comparable after acute surgery (< 12 h) and subacute surgery (12-48 h), following antibiotic treatment. The risk factors for postoperative complications in the ES group were a higher age, history of abdominal surgery, perforation, high C-reactive protein level, histological evidence of gangrenous or perforated appendicitis, a long operation time, and intraoperative complications. The risk factors for postoperative complications in the non-ES group were perforation and unsuccessful conservative treatment.

CONCLUSIONS

Non-early appendectomy is feasible for acute appendicitis but should be applied with care in patients with risk factors for postoperative complications or failure of pretreatment, including diabetes mellitus, abscess formation, and perforation.

Fulminant amebic colitis in a patient with concomitant cytomegalovirus infection after systemic steroid therapy: A case report

BACKGROUND

Amebic colitis is an infection caused by Entamoeba histolytica and most commonly observed in regions with poor sanitation. It is also seen as a sexually transmitted disease in developed countries. While amebic colitis usually has a chronic course with repeated exacerbations and remissions, it may also manifest as a fulminant form that rapidly progresses and leads to severe, life-threatening complications, such as intestinal perforation, peritonitis, and sepsis, that have a high mortality rate.

CASE SUMMARY

A 68-year-old man was admitted to our hospital with chest pain and acute dyspnea. He was diagnosed with acute coronary syndrome, acute heart failure, and bacterial pneumonia. His respiratory condition worsened despite receiving intensive care and intravenous antibiotics. On the fifth day of hospitalization, he was diagnosed with acute respiratory distress syndrome and was started on steroid therapy. He subsequently developed bloody stools and was diagnosed with cytomegalovirus (CMV) enterocolitis based on biopsy results and a peripheral blood CMV pp65 antigenemia test result. Although we started antiviral therapy with ganciclovir, which was successful in reducing his antigen titers, he continued to have bloody diarrhea. Three weeks after initiation of ganciclovir therapy and six weeks after his admission, the patient died from intestinal perforation. We only posthumously diagnosed him with amebic colitis and CMV enterocolitis based on autopsy findings of transmural necrosis of the entire colon with massive ameba infiltration.

CONCLUSION

We urge clinicians to consider Entamoeba histolytica infection if severe colitis progresses after steroid therapy. Preemptive treatment is recommended then.

Review of zoonotic amebiasis: Epidemiology, clinical signs, diagnosis, treatment, prevention and control

Amebiasis is a disease caused by the protozoan parasite Entamoeba histolytica, which mainly shows symptoms of acute diarrhea, dysentery, amebic colitis, and amebic liver abscesses. As the fourth leading parasitic cause of human mortality, E. histolytica mainly infect children in developing countries, transmitted by food and water contamination. In the majority of infected individuals, Entamoeba sp. asymptomatically colonizes the large intestine and self-limiting, while in others, the parasite breaches the mucosal epithelial barrier to cause amebic colitis and can disseminate to soft organs to cause abscesses. Metronidazole (MTZ) is the recommended and most widely used drug for treating the invasive amebiasis. No amebiasis vaccine has been approved for human clinical trials to date, but many recent vaccine development studies hold promise. For the prevention and control of amebiasis, improvement of water purification systems and hygiene practices could decrease disease incidence. In this review, we focus on the epidemiology, transmission, clinical signs, pathogenesis, diagnosis, treatment, prevention and control of the zoonotic amebiasis.

Acute appendicitis in people living with HIV: What does the emergency surgeon needs to know?

Acute appendicitis is among the commonest surgical emergencies seen in an acute setting. Individuals living with the Human Immunodeficiency Virus (HIV) and/or the Acquired Immunodeficiency Syndrome (AIDS) have an increased risk of encountering complications with acute appendicitis. We conducted a literature search using the words appendicitis and HIV in google scholar, Medline, Scopus and PubMed. The search also extended to cover HIV presented with acute appendicitis, their outcome during and following the management of acute appendicitis. Several studies showed that HIV is associated with a higher rate of acute appendicitis than the general population. HIV can directly affect the appendix, through opportunistic infections, immune reconstitution inflammatory syndrome associated with start of antiretroviral medication. High index of suspicion is needed to exclude conditions that mimic acute appendicitis (abdominal tuberculosis, pyelonephritis, cytomegalovirus, cryptosporidium, pneumococcus, Amoebic appendicitis and pill impaction). The clinical presentation may not be typical of acute appendicitis and can be associated with low white cell count and variable fever. The Alvarado score for predicting acute appendicitis can be used and more research is needed to establish cut-off point value. Computed tomography scan and ultrasound are widely used in clinical diagnosis. Importantly, acute appendicitis with HIV/AIDS can be associated with high rate of post-surgical complications like infections, delay of healing, perforation, peritonitis, intra-abdominal abscess and longer hospital stay. HIV/AIDS with acute appendicitis is complex condition. Therefore, we conclude that patients with known HIV and acute appendicitis should also be managed in close liaison with HIV physicians during, before and after surgical treatment.

Seroprevalence of Entamoeba histolytica at a voluntary counselling and testing centre in Tokyo: a cross-sectional study

BACKGROUND

Amebiasis, which is caused by Entamoeba histolytica, is a re-emerging public health issue owing to sexually transmitted infection (STI) in Japan. However, epidemiological data are quite limited.

METHODS

To reveal the relative prevalence of sexually transmitted E. histolytica infection to other STIs, we conducted a cross-sectional study at a voluntary counselling and testing (VCT) centre in Tokyo. Seroprevalence of E. histolytica was assessed according to positivity with an ELISA for E. histolytica-specific IgG in serum samples collected from anonymous VCT clients.

RESULTS

Among 2083 samples, seropositive rate for E. histolytica was 2.64%, which was higher than that for HIV-1 (0.34%, p<0.001) and comparable to that for syphilis (rapid plasma reagin (RPR) 2.11%, p=0.31). Positivity for Chlamydia trachomatis in urine by transcription-mediated amplification (TMA) was 4.59%. Seropositivity for E. histolytica was high among RPR/Treponema pallidum hemagglutination (TPHA)-positive individuals and it was not different between clients with and without other STIs. Both seropositivity of E. histolytica and RPR were high among male clients. The seropositive rate for anti-E. histolytica antibody was positively correlated with age. TMA positivity for urine C. trachomatis was high among female clients and negatively correlated with age. Regression analysis identified that male sex, older age and TPHA-positive results are independent risk factors of E. histolytica seropositivity.

CONCLUSIONS

Seroprevalence of E. histolytica was 7.9 times higher than that of HIV-1 at a VCT centre in Tokyo, with a tendency to be higher among people at risk for syphilis infection. There is a need for education and specific interventions against this parasite, as a potentially re-emerging pathogen.

Molecular epidemiology, evolution, and phylogeny of Entamoeba spp

Entamoeba histolytica is a protozoan parasite and the causative agent of amoebiasis in humans. The estimations of the worldwide burden of amoebiasis by the WHO indicated that approximately 500 million people were infected with the parasite and 10% of these individuals had invasive amoebiasis. However, our understanding of the disease burden and epidemiology of human amebiasis has undergone dramatic changes over the last two decades based on molecular analyses. The development of Entamoeba genomics has also provided some interesting and valuable information on the evolution and population structure of this parasite. In addition, the use of a number of molecular markers has greatly expanded our understanding of Entamoeba host range and genetic diversity. In this review, we re-assessed Entamoeba prevalence and species in humans, non-human primates, other animals, and the environment in the context of molecular data. Some issues regarding the evolution and phylogeny of different Entamoeba species lineages are also discussed.

A Review of the Global Burden, New Diagnostics, and Current Therapeutics for Amebiasis

Amebiasis, due to the pathogenic parasite Entamoeba histolytica, is a leading cause of diarrhea globally. Largely an infection of impoverished communities in developing countries, amebiasis has emerged as an important infection among returning travelers, immigrants, and men who have sex with men residing in developed countries. Severe cases can be associated with high case fatality. Polymerase chain reaction–based diagnosis is increasingly available but remains underutilized. Nitroimidazoles are currently recommended for treatment, but new drug development to treat parasitic agents is a high priority. Amebiasis should be considered before corticosteroid therapy to decrease complications. There is no effective vaccine, so prevention focuses on sanitation and access to clean water. Further understanding of parasite biology and pathogenesis will advance future targeted therapeutic and preventative strategies.